Clostridium botulinum produces the most poisonous toxin known and is a perennial concern to the food industry and to regulatory agencies due to the potential threat of food borne botulism. An ongoing trend within the Food Industry is the development of foods that have natural ingredients, that are free of preservatives, and that are produced under mild processing conditions. The botulinal safety of such foods can be an issue, and several outbreaks of botulism have occurred due to changes in processing procedures and formulations.
To ensure the botulinal safety of foods, rigorous microbiological challenge testing has been routinely performed using a mouse bioassay and/or in vitro assays. Microbiological challenge testing is a useful tool for determining the ability of a food to support the growth of spoilage organisms or pathogens. Microbiological challenge tests also play an important role in the validation of processes that are intended to kill or attenuate a target organism or group of target organisms. An appropriately designed microbiological challenge test will validate that a specific process is in compliance with a pre-determined performance standard. Challenge testing with C. botulinum is particularly appropriate for certain cooked products, such as products packaged under anaerobic and micro-aerophilic conditions (i.e. canned and modified atmosphere packed products) and products with a history of causing associated illness, such as products packed under oil.
Due to stringent F.D.A. regulations, testing of various foods using toxigenic C. botulinum strains require facilities that are certified for work with this organism. However, for certain applications, surrogate microorganisms are used in challenge studies in place of specific pathogens. For example, it is usually not possible or desirable to introduce pathogens such as toxigenic C. botulinum into a processing facility; therefore, surrogate microorganisms are used to test processing methods for effectiveness against C. botulinum. 
Many surrogates are closely related to but not necessarily the same species as the target pathogen. Traditional examples include the use of Clostridium sporogenes as a proxy for Clostridium botulinum in inoculated pack studies, Listeria innocua as a surrogate for L. monocytogenes, and generic strains of Escherichia coli as substitutes for E. Coli O157:H7. An ideal surrogate, however, is a genetically stable strain of the target pathogen that retains all the characteristics of target pathogen, except for the target pathogen's virulence or toxicity. Thus, the ideal Clostridium botulinum surrogates would be nontoxigenic C. botulinum strains.